1. Field of the Invention
The present invention relates to a method of planar imaging on chips; in particular, to a method of planar imaging on semiconductor chips using Focused Ion Beam (FIB).
2. Description of Related Art
Due to the advance of technology, the development on manufacturing products tend to pursue microminiaturization; in terms of the semi-conductor industry, the micro structure of the semi-conductor chips is unable to be detected through naked eyes, therefore, auxiliary machineries are required to assist men in finding the defects as well as learning the actual structures of the micro chips.
The manufacture process of a chip wherein different semi-conductor components are formed on the surface of the substrate to form a thin slice-like chip, the defect of the chips often was formed in the semi-conductor components, therefore to detect the defect features, a method of direct observation is implemented by taking a top view and extract images of the substrate position from the chip surface. The conventional method uses the Scanning Electro Microscope to form a horizontal image of the chip on the surface thereof, after the image is obtained, remove the surface layer by artificial polishing before beginning the second extraction of the image. In other words, by polishing the testing chip one time after another, the image of the testing surface is obtained gradually, so as to detect the position and the feature of the defects hidden within the chip. However, the major disadvantage of this method is that the defect features may be removed during polishing as the thickness of the layer removed through polishing is unable to get thinner, resulting the lost of opportunity in observing as well as a higher time consumption and failing rate.
As shown in FIG. 1, another conventional method of detecting defects uses the Focused Ion Beam, as ion beams in the direction of the incident ray B are perpendicularly emitted into the chip surface 2′ of the chip 1, a vertical cross-sectional view perpendicular to the chip surface 2′ is formed. However, simply using the vertical cross-sectional view which is perpendicular to the chip surface 2′ is unable to detect the defect features of the chip 1 completely. Furthermore, the testing chip has to be cut into the minimized state before examine, and this usually results the testing chip to be too thin or small, therefore easily loss during testing, resulting additional grids required to place the chip within hence raising the total expense.
Thus, polishing the chip in the testing area to extract images of different depths through electron microscope, or obtain the vertical cross-sectional view of the chip perpendicular to the testing area by using Focused Ion Beam, either method have disadvantages such as high time, human resource and money consumption and high failing rate.